1. Field of the Art
This invention relates to medical endoscopes, and more particularly to a branching passage assembly for endoscopes which incorporate a forked branching member in a manipulating head assembly to connect a proximal end of a biopsy channel to a biopsy channel entrance passage and a suction passage.
2. Prior Art
Generally, medical endoscopes are largely constituted by a manipulating head assembly to be gripped and manipulated by an operator, an insertion tube extended out from one side of the manipulating head assembly for insertion into a body cavity, and a flexible light guide cable led out from the manipulating head assembly and provided with a connector at its proximal end which is disconnectibly connectible at least to a light source. Illumination and observation windows of optical image pickup means are provided on a rigid tip end section at the fore distal end of the insertion tube to carry out an endoscopic examination of an intracavitary site of interest under illuminated state.
It becomes possible to insert a biopsy or surgical instrument through an endoscope when a diseased portion or a bleeding site is spotted within a body cavity or when there arises a necessity for sampling tissues. For this purpose, in many cases a biopsy channel is provided in the endoscope and extend between a biopsy channel entrance way which is provided on the manipulating head assembly and an instrument outlet which is opened at the distal end of the insertion tube. The biopsy channel which is extended between the biopsy channel entrance way and the instrument outlet is usually constituted by a flexible tube. The biopsy channel of this sort is also utilized as a suction passage at the time of aspiration of body fluids or the like.
In order to comply with these requirements, a forked branching passage member is provided internally of the manipulating head assembly, thereby to connect a proximal end of a biopsy channel to either a biopsy channel entrance way or a suction passage. Accordingly, the forked branching passage member is internally provided with forked passages in communication with three connecting ends, i.e., a first connecting end to be connected with the biopsy channel, a second connecting end to be connected with the biopsy channel entrance way and a third connecting end to be connected with the suction passage.
Having the construction as described above, the branching passage member has to be retained in a fixed state within the manipulating head assembly of the endoscope. In this regard, it has been known in the art, for example, form Japanese Patent Publication No. 5-3287, to provide a tubular retainer member within a casing of the manipulating head assembly and to stop a branching passage member in the tubular retainer member by means of screws.
Taking into considerations the relations with a pipe of the biopsy channel entrance way and tubes of the biopsy channel and the suction passage, the branching passage member should be fixed in the first place in a position independently of and prior to connecting thereto the pipe and tubes just mentioned. That is to say, the pipe and tubes have to be connected to the branching passage member after fixation of the latter. The suction tube which has no possibilities of damages in use can be connected to the branching passage member securely by the use of an adhesive, and a connection can be made without any difficulty in particular. However, it may be made difficult to connect the pipe of the biopsy channel entrance way, a rigid pipe, to the branching passage member even by a positional deviation therebetween. Further, considering that the biopsy channel has possibilities of being damaged by insertion of a needle-like instrument in use, it should be disconnectibly connected to the branching passage member, and should be easily disconnectible when necessary. Nevertheless, once connected to the branching passage member, the biopsy channel tube should be retained stably in the connected state. Therefore, difficulties are often experienced in connecting the biopsy channel entrance pipe and then the biopsy channel after completely fixation of the branching passage member in the tubular retainer member.